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Submitted by juanito on Tue, 07/21/2009 - 02:49
I've been comparing many different technologies concerning EV's (electric vehicles) and have been finding that they really do rock. Simple, efficient and practical EV's could be the next wave of the future. They have many many advantages over ICE's (internal combustion engines). They don't pollute as you drive them. You can even run them from solar panels and wind mills. They are so efficient that they can go over hundreds of miles on the equivalent of a single gallon of gasoline. They are reliable, having only one moving part in their motors and don't need in reality things like transmissions and driveshafts. The can slow down the vehicle and charge their batteries at the same time. They don't need oil changes or antifreeze. They can be made just as fast and powerful as any ICE out there and have the potential of doing more. What were we thinking all these years?
However, EV's have some drawbacks. Nearly all of them are related to batteries. EV's can't store enough electricity to travel long distances. They can't "fill up" very fast, perhaps taking all night to recharge. They can be affected by hot and cold weather. Some battery packs wear out rather quickly and can be quite expensive to replace. Prices seem to be quite high for the moment for all parts of EV's.
What will the future bring? Will EV's improve and adapt to the expectations of society? Will society realize that they don't need the range of ICE's and adapt to EV's? How would you picture the future?
In the beginning of the automobile industry EV's were the car of choice. They were quiet and easy to operate. Women would drive them to visit their friends and have a cup of tea. No starter, no gearshift, no smell, no dirty gasoline nor oil. You could just get in and go.
Many people think that EV's are slow dinosaurs of the automobile industry. Although that may be true of many EV's many people don't realize that it was an EV that was the first car to reach 60 MPH (100 kph). 60 MPH EV Even today some have reached record speeds and acceleration.
Back in those days you had three choices of automobiles: 1) gasoline, 2) steam and 3) electric. Gasoline engines were difficult and dangerous to start since they had to be cranked. They were also much harder to shift since automatic and synchromesh transmissions didn't exist yet. Steam cars were fast and powerful, some crusing at 60 MPH, but at the time they used more fuel than gasoline cars and cost more. Most of them also took a several minutes to reach boiling temperatures and couldn't be let freeze. But EV's didn't have any of these problems. There main drawbacks were their limited range and long charging times.
But however people wanted to go faster and further. Electric starters and better transmissions made gasoline cars more practical. Now that they were easier to use and could go a lot further they started to take over. You didn't need to wait all night for them to charge. And so the EV was left in the dust.
But as the years rolled by we started to see problems with ICE cars. Air pollution, oil dependency, gas prices and repair prices. Recently we also have seen a trend of people who don't care. Bigger, more powerful and faster seem to be what many look for in a vehicle. Safe, reliable and efficient seem to not really matter.
For EV's to be a part of our future either society needs to realize that most people only need the range of an EV or EV's need to become bigger, more powerful, faster and as good as, or better, than ICE's. Let’s look at how things are turning out so far.
Today, however, some folks have taken interest yet again in the electric car. In the 1990’s some automobile manufactures even started producing and leasing EV’s for a few years in California, USA. Although they didn’t continue, it did give rise to the hybrid car, a car that was both gasoline and electric powered. As people started to notice the advantages of driving these hybrid cars some have asked themselves what would the world be like if we be like if we all went all electric. What have they done about it.
Although today it is hard to find an EV on the market that would replace a regular sedan, some companies have started to manufacture cheep and efficient NEV’s (neighborhood electric vehicles) and scooters. These vehicles are slow and have a limited range of about 30-40 miles (depending on car, scooters are usually less), which is still plenty of range for the average driver. To double that range they can be charged at work before coming home.
A variation of the electric scooter is the electric bicycle. Just put a motor kit on your own bike and go.
In the 1990’s many car manufacturers, such as GM, Ford, Honda and Toyota, started to produce electric cars, pickups, and SUV’s that had up to a 100 mile range and could accelerate quickly up to a governed 80 MPH. Sadly, most were destroyed by their own makers. There seems to be quite the controversy as to why. (For more information see the documentary video, Who Killed the Electric Car?)
Today most electric cars are homemade conversions. In the future some manufactures have promised that there will be electric cars like the GM Volt and the Aptera 1 and other plug-in hybrids.
It may seem strange that the next step up from a slow moving NEV is a sports car but it is true. The Tesla Roadster is a fast nimble convertible for those who have a wild side. I does 0 to 60 MPH in less than 4 seconds and has a range of 200 miles. Others have made homemade electric sports cars that are even faster. With these advancements the EV may someday surpass the ICE car in every way.
But how does an EV work? What makes it different from other cars? EV’s have three main parts for their drive train: 1) the battery, 2) the motor, and 3) the controller. All of these parts play an important part in making the EV go.
In the EV world probably the most important part for determining the performance of an EV is the battery. The battery is the fuel tank of the EV and its size and type set out the range of the car. What sets out its capabilities? EV batteries are composed of cells, like the AA, AAA, C and D size batteries which really aren’t batteries, rather cells or piles. Each cell has a certain voltage. To get a greater voltage the cells have to be connected end on end (positive to negative) which makes a series. For an example six 2 volt cells in a car battery are put end on end in a series to produce 12 volts. You can make up to hundreds of volts this way. The size of the cells determines how much current they can produce over a certain period of time. You can also increase this by connecting series of cells with other series in a parallel connection (positive to positive, negative to negative).
But another important factor is the type of battery that is being used. What kinds of batteries are out there and what kinds may be part of the future?
Lead acid batteries have been around as long as the EV itself. They are cheap and durable. But lead acid batteries don't hold a lot of energy for their weight and don't last very long. They also contain sulfuric acid which can burn, although GEL and a few other types can't leak. They also produce an explosive mixture of hydrogen and oxygen and are harmful for the environment when disposed.
Lead acid batteries are used in many NEV's and small vehicles and were the original batteries on the EV1 electric car. Even though they are rather low quality batteries compared to others, they do have plenty of power to fuel a car up to double the average 30 mile range that 90% of Americans need for their daily lives.
NiMH (nickel metal hydride) batteries hold more electrical energy than lead acid ones. They also last some 5 times longer. What else I like about them is that they aren't as harmful for the environment. They also seem easier to recycle. They do however have some strange charging characteristics and can be easily damaged by overcharging and discharging which means they need a special BMS (battery monitoring system). An older battery that is similar but contains toxic cadmium is the NiCad.
NiMH batteries are used in many hybrid cars including the Toyota Prius and were the battery of choice for many EV's of the 1990's.
Li ion (lithium ion) batteries can hold tremendous amounts of electrical energy for their size. But they tend to wear out quite fast. Even if not used they can lose some 20% of their original capacity per year. They are also explosive and can be bad for the environment.
Li ion batteries are used in small portable devices like cellular phones and laptops.
Li ion batteries are good for drag racing applications.
LiFePO4 (lithium ferrous phosphate) batteries are right now about the best battery for EV's you could buy. They have a high energy density and last 10 times as long as lead acid. They don't explode nor do they leak acid or explosive gases. They also don't contain harmful elements. If I were to build an EV right now I would use LiFePO4 batteries.
Thin cell lithium batteries are rather new but may hold a bright future. They hold twice as much energy as Li ion batteries of the same size and last 200 times longer than lead acid batteries or better.* Beat that!
Thin cell li batteries are currently used in things like pacemakers.Thin cell
Ultracapacitors are unlike any conventional battery. Instead of using a chemical reaction to generate electricity they store electricity by capacitance. This means that they can be charged almost instantly, granted that you have a charger that can put that much electricity out. Many ultracapacitors sold today will last tens of thousands of times longer than lead acid batteries. They are also non toxic and don't explode. The only disadvantage (beside cost) is the fact that they don't hold a lot of energy.
So for now they could find a use only as supplementary sources of energy to batteries for those moments that you want to accelerate quickly. Or possible be used in drag racing applications.
But improvements are under way. Already ultracapacitors have been made to equal the energy density of lead acid batteries. Ultracapacitors At least on company even has promised that by the end of this year, 2009, it will have in production ultracapacitors that will far surpass even the best lithium batteries out there.Zenn Cars In the future I suspect that electricity could be stored in gigantic ultracapacitors at fuel stations. They could charge up each vehicle's capacitor bank in minuts, even seconds as long as wires are designed to withstand the amperage. But if you wish you could still charge them up overnight at home.
COMPARISON OF BATTERIES
*Best as of now. But with leaps and jumps in technology who knows what we’ll have next.
Hate changing oil? Hate trying to find out which part of the motor is not working right? Well look no more! Electric motors don't need oil changes and only have one moving part. What's cool about E-motors is that they work perfectly for vehicle purposes. An E-motor can start from a stop and go in reverse. Unlike an ICE they also have max torque from a stop, when you need it the most. They don't need a transmission. They even can be made as part of the wheel itself. You can also use them to slow down your car and at the same time partially charge the battery. E-motors can also be temporarily run on over-volt which supercharges them for fast take offs until they over-heat. Motors
Each kind of motor has its own characteristics but they all work on the same principal, magnets. In school you probably remember your teacher showing you the effects one magnet can have on another. If you put two of the same kind of poles together, north north or south south, then they push apart. But if you put a north and south together they attract. Well in any electromotor electro magnets push and pull on stationary magnets. Just when two magnets meet up the current is reversed, changing the poles of one of the magnets, and therefore making them repel each other. So as you can see, even though many motors are called "DC motors", all E-motors run on AC on the inside. AC or DC just refers to the kind of current entering the motor or its controller.
Now generally speaking, E-motors follow these basic rules:
1 At a stop the motor has the greatest torque. The faster the motor goes the more the torque diminishes.
2 At a stop the motor draws the most current. The faster it goes the less current it draws.
3 You can raise the current and torque by raising the voltage (electric pressure) as long as it doesn't overheat.
4 If the voltage is lowered or the motor is spun fast enough the motor will push electricity backwards back into the batteries. (A motor and a generator are the same thing.)
All electric motors are similar in these respects. But E-motors come in many shapes and sizes and kinds. What are some of the basic differences? Here are some of the basic options:
AC (alternating current) motor or DC (direct current) motor
PM (permanent magnet), wound field or induction motor
On wound field motors: series type, shunt type or compound type
Brushed or brushless
Permanent magnet motors are simple motors, and can be made to be very powerful as well as efficient. Their only drawback is that they are usually efficient in only a very small RPM band. But continuously variable transmissions and modern electronics have the potential to make PM motors efficient in a larger RPM range.
PM motors come in two main types: brushed and brushless. Brushed types use regular DC current and convert the DC current to AC by contact between the brushed and the communicator. Brushless DC motors (BLDC’s) need a special AC current in order to run. In order to do this they need a special controller that uses DC current. Brushless motors are maintenance free whereas brushed motors will need new brushes after a while.
Most toys us PM motors.
AC motors are very useful in vehicle applications. But they need a converter that converts DC current into regular AC current. AC motors come in basically two types: brushless (induction) or brushed. The brushed type is like the field wound motors that we shall discuss next. The brushless type, on the other hand, is very different. They contain coils around a rotor composed of bars of iron. As the alternating current passes through the coils the magnetic field produced induces a magnetic field in the iron bars. This causes them to push and pull against each other and spins the rotor.
AC motors are used in household appliances like blenders and vacuum cleaners.
Field Wound Motors
Field wound motors don’t have permanent magnets in them. Rather they have electro magnets that use the same current as the rotor to produce magnetism. They come in three types: series, shunt and compound. Each behaves differently due to the way they are wired. Of the three, series type motors seem to be the best for EV applications. They have a fairly good efficiency in a broad RPM range and are great for EV’s.
Even today, highly efficient high powered super-conducting motors have been developed. These motors are usually a third of the size of other electric motors and have the same power. This is astounding since even modern electric motors are already powerful for their size. I can just imagine busses and large trucks with little tiny motors as powerful as the big diesel motors they have now!
Motors come in many different sizes and are built for many different purposes. Some are already designed to couple directly to the existing driveshaft of some vehicles. Others are designed to replace the hub and turn the wheel directly. However, many homemade vehicles have to be home fabricated for a commercial motor to fit.
The controller is like the carburetor on you ICE car (or fuel injectors). It controls the amount of electricity that goes to the motor. In an EV the throttle pedal or twist grip is connected to the controller. When you let your foot off the pedal the controller is signaled to cut off the current to the motor. Flooring it makes it turn the current on completely. Anywhere in the middle and the controller rapidly turns on and off the current to the motor and therefore limits the speed. Some have a voltage converter inside which causes the motor to act like a generator and slows down the vehicle and charges the batteries when you step on the brake pedal.
Compared with carburetors and fuel injectors and transmissions, motor controllers are easier to install, are universal for any specific type and size of motor and, since they have no moving parts, should last longer. Plug this into the battery; that into the motor; here’s the throttle; who cares if it’s a Ford or Chevy?; and let’s go!
So hope you’re a little more familiar with EV’s. They make so much more sense than gasoline, diesel, hydrogen, nitrogen, sterling and steam cars. Most people don’t need to drive much more than some 30 miles a day. If that is all you need, then why don’t you go down and buy a NEV for less than $10,000 and drive it for a tenth the price it would cost you in a gasoline car? You wouldn’t have to change the oil, nor spark plugs nor filters. No carbon monoxide poisoning nor spilt fluids. No more going to the gas station and cringing at the sudden changes in prices. Maybe later you could put up some solar panels on your roof and drive for free and save the environment. Could it really get any better than that?